Note:The figure (left) shows anomalies for March snow mass in the EEA region (excluding mountain areas) and the 30-year linear trend.
The map (right) shows a snapshot of snow cover on 15 February 2009.

Note:The figure shows the multi-model mean of changes in annual snowfall days from 1971-2000 to 2041-2070 exceeding (left) 1 cm and (right) 10 cm based on six RCM simulations and the emission scenario A1B

Key assessment

Past trends

Satellite observations on the monthly snow cover extent in the Northern Hemisphere are available since November 1966 [i]. Figure 1 shows that snow covered on average 45 % of the land area of the Northern Hemisphere in winter (December to February), varying from less than 41 % in 1980–1981 to over 48 % in 1977–1978 [ii]. Satellite data shows that there are no trends from 1967 to 2010 in snow cover in fall (September-November) and winter (December-February), but snow cover in spring has decreased significantly. According to a detailed statistical analysis of the snow cover in the Northern hemisphere the rate of decrease in March and April in the period 1970–2010 was around 0.8 million km2 per decade, corresponding to a 7 % decrease in March and an 11 % decrease in April from the pre-1970 values [iii]. Trends in snow cover vary in different parts of Europe. In some mountain regions, such as the Alps and the Norwegian mountains, snow depth has decreased at low elevations where the temperature increased over the freezing point whereas it has increased at high elevations where both precipitation and temperature have increased but the temperature has remained below the freezing point for extended periods [iv]. In other mountain regions such as the Carpathians, Tatra, Pyrenees, and Caucasus, there have been either decreasing or variable trends [v][vi]. In the lowlands of western Europe, snow is not a permanent winter phenomenon — it may come and go several times during the cold months. Decreasing snow cover trends have been observed in, for example, Britain[vii], Germany[viii], Poland [ix] and Nordic countries[x]. In general, snow conditions in these areas correlate strongly with large-scale circulation patterns as indicated by the NAO [xi][xii]. The snow mass (i.e. the amount of water that the snow contains) is another important variable describing seasonal snow. In the Northern Hemisphere, a 7 % decrease has been observed between 1982 and 2009 for March[xiii]. An extension of this data focusing on EEA member countries, excluding mountain areas, also demonstrates this decline (Figure 2).

Projections

The seasonal snow cover is likely to continue shrinking [xiv]. Figure 3 shows projections of changes in annual snow fall days based on a multi-model ensemble. The multi-model mean shows decreases in days with snow fall exceeding 1 cm across Europe. Days with snow fall above 10 cm show increases in large parts of northern Europe and decreases in most other regions. There is, however, considerable uncertainty in these projections due to large differences between the upper and lower limits of the model projections. Because snow cover is sensitive to snowfall as well as temperature, increased snowfall will not necessarily translate into more snow on the ground [xv]. A study has projected a reduced number of snow cover days in northern Europe (defined as 55–70 °N, 4.5–30 °E) of up to 40–70 days in 2071–2100 compared to the baseline period 1961–1990. The study used a RCM driven by an ensemble of 7 GCMS for 4 SRES emission scenarios[xvi]. The projections depend on the emission scenario and the underlying GCM simulation. Model projections of 21st century change in snow water equivalent (SWE) in the Northern Hemisphere under the SRES A1B emissions scenario suggest that SWE increases in the coldest parts of the Northern Hemisphere continents, but decreases elsewhere [xvii]. The multi-model mean from the CMIP5 modelling exercise projects changes in March/April snow cover in the Northern Hemisphere during the 21st century of about 7 % and 27 % in a low emission scenario (RCP 2.6) and a high emission scenario (RCP 8.5), respectively [xviii]. Despite the projected decrease in long-term mean SWE in the Northern Hemisphere, model simulations indicate occasional winters of heavy snowfall, but these become increasingly uncommon towards the end of the 21st century. Significant reductions in snow mass in Europe are likely to occur in Switzerland[xix], the alpine range of Italy[xx], the Pyrenees[xxi], the Turkish mountains[xxii] and Balkan mountains [xxiii]. In these areas the change can have dramatic effects as melt water contributes up to 60–70 % of annual river flows.

Justification for indicator selection

Snow influences the climate and climate-related systems because of its high reflectivity, insulating properties, effects on water resources and ecosystems, and cooling of the atmosphere. A decrease in snow cover contributes to accelerated climate change.

In Europe about half of the 800 million people live on areas that have snow cover in January in an average winter. Changes in snow cover affect human well-being through effects on water availability, hydropower, navigation, infrastructure, the livelihoods of indigenous Arctic people, environmental hazards, winter recreation and outdoor light conditions. Variation in snow cover affects winter road and rail maintenance, and the exploitation of natural resources in cold regions. Snow cover is most sensitive to climate change at low elevations in temperate regions.

Scientific references:

No rationale references
available

Policy context and targets

Context description

In April 2013 the European Commission presented the EU Adaptation Strategy Package (http://ec.europa.eu/clima/policies/adaptation/what/documentation_en.htm). This package consists of the EU Strategy on adaptation to climate change /* COM/2013/0216 final */ and a number of supporting documents. One of the objectives of the EU Adaptation Strategy is Better informed decision-making, which should occur through Bridging the knowledge gap and Further developing Climate-ADAPT as the ‘one-stop shop’ for adaptation information in Europe. Further objectives include Promoting action by Member States and Climate-proofing EU action: promoting adaptation in key vulnerable sectors. Many EU Member States have already taken action, such as by adopting national adaptation strategies, and several have also prepared action plans on climate change adaptation.

The European Commission and the European Environment Agency have developed the European Climate Adaptation Platform (Climate-ADAPT, http://climate-adapt.eea.europa.eu/) to share knowledge on observed and projected climate change and its impacts on environmental and social systems and on human health; on relevant research; on EU, national and subnational adaptation strategies and plans; and on adaptation case studies.

Adaptation means anticipating the adverse effects of climate change and taking appropriate action to prevent or minimise the damage they can cause, or taking advantage of opportunities that may arise. It has been shown that well planned, early adaptation action saves money and lives later. This webportal provides information on all adaptation activities of the European Commission.

In April 2013 the European Commission adopted an EU strategy on adaptation to climate change which has been welcomed by the EU Member States. The strategy aims to make Europe more climate-resilient. By taking a coherent approach and providing for improved coordination, it will enhance the preparedness and capacity of all governance levels to respond to the impacts of climate change.

Methodology

Methodology for indicator calculation

Satellite observations on the monthly snow cover extent in the Northern Hemisphere are available since November 1966 from the Rutgers University Global Snow Lab and from the Globsnow project. Trend lines have been added.

Multi-model mean of changes in annual snowfall days from 1971–2000 to 2041–2070 exceeding 1 cm and 10 cm are based on 6 RCM simulations and the emission scenario A1B.

Methodology for gap filling

Not applicable

Methodology references

No methodology references available.

Uncertainties

Methodology uncertainty

Not applicable

Data sets uncertainty

Data on the cryosphere vary significantly with regard to availability and quality. Snow and ice cover have been monitored globally since satellite measurements started in the 1970s. Improvements in technology allow for more detailed observations and higher resolution. High quality long-term data is also available on glaciers throughout Europe.

Continuous efforts are being made to improve on knowledge of the cryosphere. Intensive development work is under way to develop projections, which are essential for scenarios of climate change impacts and adaptation. Due to their economic importance special effort is also devoted to improving real-time monitoring of, for example, snow cover.

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